As the sizes of internal parts of electronic products such as mobile phones, laptops, hearing aids are becoming smaller and smaller, a large amount of small-size, high-quality and low-cost miniature condenser microphones are being applied. At present, miniature condenser microphones available in the market generally have a volume of tens of cubic millimeters. In view of this size requirement, the traditional design of a miniature condenser microphone, in which the fundamental structure comprises a protection frame composed of a metal casing and a circuit board, a plastic enclosure installed inside the protection frame to play a supporting and insulating role, a metal grating ring mounted inside the enclosure for circuit conduction, and capacitance components connected to the grating ring, will inevitably negatively affect the performances of its products since the sizes and the amounts of the internal parts thereof are both large. There exists a tradeoff between the size and the performances of a product from the viewpoint of technology. Therefore, a newly structured condenser microphone was disclosed in the prior patent CN200710129770.6, wherein a protection structure is composed of a circuit board substrate and a frame body, sound holes for receiving external signals are provided on the protection structure, a vibration diaphragm, an isolation spacer and a backplate are sequentially arranged inside the protection structure, the backplate is kept elastically and electrically connected to the circuit board substrate through an elastic holding component made of spring materials, and the vibration diaphragm may be electrically connected to the circuit board substrate through circuits inside the frame body. The structure of the product can, to some extent, lead to a reduction in the size of the product, however, there exists in the structure a certain gap between the backplate and the inner side walls of the frame body so that the backplate can move freely within the frame body, and its position can only be determined by the elasticity of the elastic holding component. In case that the product stays in a relatively stable state, the backplate can be stably secured by the elastic holding component, and be electrically well-connected to the circuit board substrate. When the product is in a state of sharp acceleration, for example in a falling test, a plurality of drawbacks may appear. For example, a relatively large force may be fully applied to the elastic holding component by the backplate, resulting in a sharp compression that could cause an excessive deformation of the elastic holding component and thus a reduction in the resilience thereof, so that the electrical connection between the circuit board substrate and the backplate may turn out to be unstable or even broken. Moreover, because the amplifier is usually mounted near the central portion of the circuit board substrate, a relatively large force may cause the portion of the substrate where the amplifier is mounted to deform in a direction towards the backplate. This situation may also result in a compression deformation in the elastic holding component, so that a collision between the backplate and the amplifier device may occur and thus lead to various undesirable consequences such as damages to the amplifier device.
Therefore, there is a need to design a newly structured condenser microphone with higher reliability, and make the products thereof thinner and smaller without causing various drawbacks.